Primarily, I'm talking about my OM-D and even my GX-1. I bought both used off this board a while back and I've used them a lot, though not nearly as much as I want.

I've swapped lenses many times out in the field, exposing the sensor for the world to see and dust devils to latch on to - a result of shooting primarily primes, though I do have the 12-50 and 100-300 for zooms.

I've shot small apertures (f11/f16) for macro and landscape DOF, yet nothing. No dust, well almost.

This weekend processing a GX-1 shot, I finally found two faint halos signifying dust. It's about damn time - I was starting to get bored.

Anyone else notice this?

I've literally gone through all the major brands (save Leica, etc) at least once and I've never had this type of anti-dust performance - hell even my A77 managed to get more dust on its sensor, and that dust had to make it past the clear mirror.

Yup. I almost never have to clone dust out of my images. I think I might have had to do it once, and use a rocket blower when something got stuck on my E-P1. I don't think I've had a visible dust spot with my GH2, GX1 or E-M5. The Olympus sensor-shake system (Supersonic Wave Filter) is phenomenal. Panasonic licenses it from Olympus, so all their bodies have it too. Evaluations of all the anti-dust technologies consistently place the Olympus system well above those from other manufacturers.

I never saw any problems when I had my GF-3. However, I practically only shoot between f1.4 - f8.0 in general so dust usually isn't too noticeable to me. What's the difference between Olympus' sensor shake system compared to ones used by Nikon, Sony, and Canon?

Yes, my old G1 (first mirrorless) was same. Tho old 4/3 cams were too, I think they inherited same high frequency antidust filter. Anyway it worked great, had it for year and half and not a single speck.

Same here with the GH2. My GH1s had to be cleaned about once in 6 months of hard use. "Had to be" = one spec of noticeable dust where the "Clean Sensor" menu item had to be selected 2 to 5 times in a row manually to get it off. I guess I've had the GH2 about 6 months already but no dust specs yet.

And I should add that I live in a 100 year old mud house and mud houses are total dust factories - especially older ones.